Atheism is a belief system of deriding and denigrating believers of ancient mythologies in an attempt to better understand our existence, and to deride the choice that religious people have found that works for them in explaining the very same thing. Atheism is opting-out, rather lazily, and then feel the need to feign superiority over everyone else, when, they're not at all superior. They're not IN-ferior either, but they lack humility. If anything, Atheism is like an extremist form of Agnosticism. At least Agnostics have the humility to say "I don't know." They stop there, usually. There's no need to condemn or ridicule people who embrace religion. Maher has even done that quite a few times. He waivers between agnostic and atheist. He goes full-blown atheist when he's making a living denigrating religious people for claiming they know exactly how we got here and why we're still here and how we'll no longer be here when this body fails. He does it moreso when the religious people insist that their religion is the only "correct" religion. And, I agree with him that thinking like that is potentially dangerous to the rest of us.
Atheism is a theory, too. I think Atheists have a problem with the use of the term "God." To say "God" makes them recoil and they think they've fallen back into an ancient religion... which they spend their off hours ridiculing. I don't ridicule religion. I'm critical of it. But, I'm only critical of it when the subscribers insist that their religion is the ONLY "correct" religion. If religious people could show more humility, we'd get along better. If all people(myself included) could show more humility, we'd get along better!